The present invention relates in general to a brake assembly for rollable articles, and more particularly, to a single acting brake assembly for simultaneously braking a plurality of wheel assemblies.
Floor supported movable articles such as cabinets, utility carts and tables are widely used in industry and business such as in offices, restaurants and factories, as well as on aircraft. These movable articles typically include a plurality of wheel assemblies to facilitate their movement from one location to the next. It is generally known to provide a braking assembly for locking the wheel assemblies to preclude their movement in certain circumstances. However, many of the known braking assemblies do not perform well in certain situations. For example, aircraft galley carts are required to be moved within narrow seat aisles which typically prevent movement of a flight attendant from one end of the galley cart to the other. This restricted access to the ends of the galley cart require a braking assembly capable of being operated by one person from a position on either end of the cart. Due to the nature of aircraft galley carts, the brake assembly should be capable of braking the wheel assembly even when the cart is heavily loaded and when the floor in the aircraft cabin is sloped, for example, during take-off and descent.
To this end, there is known brake assemblies which are activated by means of a foot pedal which enables the operative engagement of the brake assembly with the wheel assemblies.
For example, brake assemblies for aircraft galley carts are known from Felton, U.S. Pat. No. 5,244,062, Collignon, et al., U.S. Pat. No. 4,793,445, Nordskog, U.S. Pat. No. 4,679,662, and Schmidt, U.S. Pat. No. 4,526,253. In Felton, a brake assembly is arranged at both ends of the galley cart which is operative in only one direction irrespective of whether a braking or a releasing operation is to be performed. This is accomplished by a brake pedal being connected to a cam follower through a swivel bar. The cam follower is positioned within a cam track which is operative for locking and unlocking the wheel assembly.
In Collignon, et al., there is provided a single acting brake assembly which simultaneously brakes two wheel assemblies of a utility cart. The brake assembly includes a bracket mounted between the wheel assemblies to be braked. A longitudinal frame assembly, having wheel engaging brake shoes, extends between the wheel assemblies and is slidably mounted to the bracket for vertical movement with respect thereto. A cam member is pivotably mounted between the bracket and the frame assembly. Pivoting the cam member effectively moves the frame assembly relative to the bracket, which engages brake shoes against the wheels within the wheel assemblies.
In Nordskog, an aircraft galley cart is provided with a braking plate having a notched outer periphery which is secured to one side of a wheel assembly. A braking assembly includes a rubber ball operatively coupled to a brake pedal which is engagable within one of the notches for locking the wheel assembly in a non-rotatable condition.
In Schmidt, a pair of rotatable eccentric cams are mounted on the bottom of an aircraft galley cart at either end thereof. The cams cause transverse movement of an associated brake rod having its ends located to actuate a spring loaded brake pin into a locked position with respect to the wheel assemblies. The cam is operatively rotated by separate locking and unlocking brake pedals arranged in pairs at both ends of the galley cart.
In order to meet the rigid demands of these galley carts, brake assemblies are required which are sturdy, while at the same time ensure positive locking of the wheel assemblies. The inadvertent rolling of a galley cart when in use, or during take-off or descent of an aircraft, can cause serious injury to passengers, flight attendants, as well as to the aircraft itself. At the same time, it has been found that these known brake assemblies considerably increase the weight of the galley cart, and in certain cases, are constructed in a manner which exceeds their mechanical requirements. In this regard, conventional aircraft galley carts are known to be relatively heavy and cumbersome, including heavy duty wheel assemblies, brackets and the like such as known from Schmidt. The extra weight and cumbersomeness of these brake assemblies significantly make these galley carts more difficult to move and manipulate within narrow seat aisles, as well as more expensive to manufacture and repair.
There is therefore an unsolved need for a brake assembly for rollable articles such as utility carts, in particular aircraft galley carts, which remedy the above-mentioned drawbacks and which provide a brake assembly which is easy to operate, which requires little maintenance and adjustment, and which permits safe braking even during turbulent conditions of the aircraft.